Yamaguchi YMV-60 spindle noise

[Aaronh]

All,

I managed to get my mill running tonight. It hasn't run for a year and a half at least. I started moving the axis a little. Then I ran the spindle. I started by running it slow, 100 rpm at first. I let it run for a couple minutes, then stopped it for a minute or so, then started it again. After a few minutes of that I ran it at 500 rpm, then 1000. Everything seemed to be going well. Then I got brave. I started it back up at 1000 then kicked it up to 2000. It ran for a few seconds, then made a sort of a squawk sound and now the spindle makes noise. It not tremendously loud, but noticeable. Definitely not good as the load meter is higher now than before the noise. I noticed that when I was running it at 100 rpm before the noise the spindle speed was not very steady. It would speed up/slow down and the load meter fluctuated between 5% and nearly zero. Now the load meter is at least 10% @ 100 rpm after the noise. I ran the spindle (with no tool holder) on and off for around 20 minutes or so give or take. Not sure if there is an issue with the servo? I sure hope it's not the spindle bearings. Anyone have any ideas of what to look at first?

Thanks,
Aaron

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[Aaronh]

I investigated a bit further this morning. I am quite certain it is in the servo. The link below is a short video of it running. The first half is 100 rpm, then I sped it up to 500 rpm.

https://plus.google.com/104092800892...ts/AThiM2Chh7R

[underthetire]

Sounds a lot like a upper bearing failure or a built in sensor problem, if it has one. Would help to know what kind of spindle and control

[Aaronh]

Thanks for the reply. I took the belts off. No question it's the motor. It's a Fanuc 6M control.

[underthetire]

Does it have a Fuji spindle motor then?

[Aaronh]

[Aaronh]

I checked the resistance between all 3 windings. They're about the same as far as my meter could tell, 0.7 ohms. No winding was shorted to ground. I did find something interesting, however. While running at 500 rpm the voltage across the three motor phases ranged from 50 to about 100 volts. I would think they should be a lot closer than that. I checked the voltage at the main disconnect of the machine and got 234-242 volts. I have this running on a phase converter that I have used previously with my Mazak lathe with T1 control.

[underthetire]

Make sure you have the switch on the spindle drive set to the higher voltage setting. I'm thinking the sensor in the motor is causing your issues.

[Aaronh]

I found the switch you are talking about. It is set to the higher voltage.

[Aaronh]

How do you verify the sensor in the motor is working properly? My concern is that there is something wrong in the drive itself since the voltage between two legs was around 50 volts, but two other legs was around 100. I'm afraid it's the SCR's or something else on the boards.